The focus of this Level l application is the identification and testing of strategies for using own mothers' milk (OMM) to provide protection from infection for extremely low-birthweight (ELBW; <1000g) infants. Immunoincompetence plus exposure to pathogenic microorganisms in the neonatal intensive care unit (NICU) predispose ELBW infants to nosocomial infections, which result in short-and long-term sequelae, and increase the cost of the NICU stay by a mean of $ 10,440 per infection. Clinical studies have documented a lower incidence and severity of nosocomial infections in OMM-fed than formula-fed preterm infants. Immunologic research has identified specific protective factors in OMM that provide passive and active immunity for the infant; many are concentrated more highly in OMM from mothers of preterm than term infants. Selected immunologic factors, such as secretory immunoglobulin A, are absorbed and excreted in the infant's urine; lactoferrin, with enhanced bacteriocidal properties, has been recaptured from feces. Thus, OMM may provide significant protection for ELBW infants; additionally, OMM is inexpensive, and facilitates mothers' participation in infant care. The dissertation will test strategies for using OMM to provide protection from infection during the early post-birth period when ELBW infants cannot tolerate enteral nutrition. An example is the use of OMM for routine infant mouth care and/or for gut-priming, e.g., minimal enteral feedings that stimulate maturation and barrier protection of the gastrointestinal tract. Outcome measures might include whether specific immune components of OMM are recaptured in infants' urine and feces.